Helical CT of the urinary organs.

Despite of the diagnostic potential of conventional CT (CCT), limitations being inherent in this technology reduce its diagnostic confidence and limit clinical CT applications as 3D imaging. Helical CT (HCT) has far overcome the limitations of CCT and has become the standard CT technology. After a short overview on the technique of HCT and its advantages over CCT, the impact of HCT on the detection of disorders of the urinary organs is discussed. Due to the high quality of 3D reconstructions, vessels are visualized free of artefacts resulting in a dramatic improvement and acceptance of CT angiography, which has become a clinically important examination in the evaluation of obstructive renal artery disease. Fast HCT provides a precise assessment of the three phases of the nephrogram and it is a prerequisite for an improved depiction of abnormal vascular perfusion and impaired tubule transit of contrast material. Helical CT enables an improved characterization of cystic mass lesions reducing the diagnosis of indeterminate masses and thus facilitating a better therapeutic management. The diagnosis of renal cell carcinomas (RCC) has improved due to an increased sensitivity in detecting small RCCs, and an increased specificity in the diagnosis of neoplastic lesions. Improved staging of RCCs is the result of accurate assessment of venous tumour extension. When planning nephron-sparing surgery 3D display of the renal tumour helps to determine the resectability of the mass depicting its relation to major renal vessels and the renal collecting system. In the evaluation of renal trauma HCT provides shorter scanning time and thus fewer artefacts in the examination of traumatized patients who cannot cooperate adequately. Three-dimensional postprocessing modalities allow the assessment of the renal vascular pedicel by CT angiography and improve the demonstration of complex lacerations of the renal parenchyma. In the evaluation of the upper urinary tract unenhanced HCT has become the imaging method of choice in the diagnosis and differential diagnosis of acute flank pain since it is highly sensitive and specific in detecting calculus disease. Unenhanced HCT may furthermore demonstrate causes of flank pain unrelated to urolithiasis. Gapless volume scanning and improved resolution in the z-axis during the excretory phase enables improved visualization of the renal collecting systems and ureters, resulting in a better demonstration of intraluminal and extraluminal pathology.

Renal masses--evaluation by amplitude coded colour Doppler sonography and multiphasic contrast-enhanced CT.

OBJECTIVE: To assess the efficacy of amplitude coded colour Doppler US (aCDS) in the evaluation of renal masses as shown by multiphasic contrast-enhanced CT. MATERIAL AND METHODS: Eighty patients (155 kidneys) with suspicion of renal masses underwent aCDS and spiral CT. The findings were classified into normal kidneys, kidneys with tumours, kidneys with cysts, and those with "other findings" (i.e. bleeding, calcifications, inflammation, parenchymal hypertrophy). The aCDS findings were compared to CT results and to histological findings or clinical, laboratory and follow-up data. RESULTS: Eighteen renal cell carcinomas and 8 other tumours were found; 78 kidneys had cysts, 12 polycystic kidneys and 10 fibrotic kidneys were detected, 20 kidneys showed other findings. Diagnostic aCDS data were obtained in 129 kidneys (83.2%) showing pathology with an accuracy of 94%. CT adequately showed pathology in all patients with some diagnostic uncertainty in the evaluation of complicated cysts. CONCLUSION: Though contrast-enhanced multiphasic spiral CT is the method of choice for evaluating renal masses, US including aCDS can provide valuable information, particularly in differentiating vascularized from non-vascularized lesions and in the evaluation of complicated renal cysts.

[Benign non-organ-related diseases of the retroperitoneal space]. / Benigne, nicht organgebundene Erkrankungen des Retroperitonealraumes.

Because of the anatomic localisation of the retroperitoneal space, the detection and elucidation of pathology in the retroperitoneum calls for clinical acumen and the utilisation of imaging techniques. During the past two decades, efforts spearheaded by the work of M. A. Meyers led to an enhanced understanding of retroperitoneal anatomy and pathology. Conventional radiographic techniques are often incapable of detecting and/or characterising retroperitoneal abnormalities. Sonography may be limited by patient-dependent-factors. CT is unaffected by bowel gas and provides discrete cross-sectional images of the organs, fascial planes and retroperitoneal compartments, making it an ideal tool for assessment of retroperitoneal disease. In clinically stable patients MRT may be a useful modality for providing helpful and additional information in characterising retroperitoneal abnormalities. In this review article the diagnostic possibilities of benign not organ-related diseases of the retroperitoneum are described. This is intended to give the reader an insight into the etiology and distribution patterns of retroperitoneal fluid and gas collections as well as into diagnosis and differential diagnosis of benign retroperitoneal diseases. The diagnostic impact of the different imaging modalities is discussed.

Endovascular treatment of renal artery aneurysms with conventional non-detachable microcoils and Guglielmi detachable coils.

OBJECTIVE: To evaluate the efficacy and safety of endovascular occlusion of true renal artery aneurysms (RAAs) with conventional non-detachable microcoils (NDCs) and Guglielmi detachable coils (GDCs). PATIENTS AND METHODS: Over a 5-year period, 12 RAAs were treated by endovascular selective embolization. Four RAAs were occluded using NDCs and eight were treated with GDCs. All coils were delivered through a microcatheter. Eight RAAs were located in the bifurcation of the main renal artery, two in the main renal artery and two were intrarenal. Before treatment, four patients presented with hypertension, one associated with renal infarction and a second had flank pain due to microembolization. Two other patients had renal infarction, associated with haematuria in one; one other patient also had haematuria and five patients were asymptomatic. All patients were followed using clinical and angiographic examinations after 6 months, 1 and 2 years. RESULTS: All RAAs were occluded successfully. In two patients treated with NDCs there were minor complications, i.e. one subsegmental peripheral infarction and one misembolization, both without clinical symptoms. In the group treated with GDCs there were no complications. Five of seven patients were clinically improved, while two patients remained clinically unchanged. CONCLUSION: Superselective endovascular treatment of RAAs with microcoils is a safe, efficient, and less invasive alternative to surgical treatment. The high flexibility and softness of the GDC and the controlled detachment enables a safer and more complete occlusion of RAA than current alternatives.

[Endovascular embolization treatment for intractable epistaxis]. / Endovaskuläre Embolisationsbehandlung bei unstillbarer Epistaxis.

BACKGROUND: Intractable epistaxis has been treated with surgical intervention for many years, including ligation of the internal maxillary artery. As an alternative approach, endovascular therapy has gained increased acceptance. The purpose of our study was to evaluate the efficacy and safety of endovascular treatment of untractable epistaxis. METHODS: Embolotherapy was performed in 26 patients. The indication for embolization was persistent epistaxis even after anterior and posterior nasal packing. In all but two patients, who required general anesthesia, the procedure was performed in local anesthesia. Endovascular embolization of the internal maxillary artery was performed by using microcatheters, which were introduced intraarterially. Particulate embolic agents were used in all but one patient, who was treated by means of minicoils. RESULTS: The embolization of the territory of the internal maxillary artery was possible in all cases, the technical success rate was 96%, the clinical success rate was 100%. No complications were encountered. Because of an acute recurrent bleeding in one case, a second embolization was performed. No delayed hemorrhages were noted. CONCLUSIONS: Endovascular embolotherapy seems to be an excellent, safe, and less invasive alternative to surgery in patients with intractable epistaxis.

Multiphasic helical CT of the kidney: increased conspicuity for detection and characterization of small (< 3-cm) renal masses.

PURPOSE: To evaluate the potential of thin-section multiphasic helical computed tomography (CT) in the detection and characterization of small (< 3.0-cm) renal masses. MATERIALS AND METHODS: Identically collimated helical CT of the kidney was performed before and after administration of contrast material in 93 patients with small renal masses. Helical CT scans were obtained during the corticomedullary and nephrographic phases. Differences between attenuation of the lesion and that of the kidney were measured quantitatively. The presence of a mass or absence of disease was confirmed with clinical, imaging, and histologic findings. RESULTS: The number of masses smaller than 3.0 cm detected on corticomedullary-phase scans (n = 211) was statistically significantly fewer than those on nephrographic-phase scans (n = 295) (P < .01). Mean differences in enhancement between the renal cortex and masses were 148 HU +/- 54 and 137 HU +/- 44 during the corticomedullary and nephrographic phases, respectively, and the difference in attenuation of the renal medulla and that of the masses was statistically significantly greater during the nephrographic phase (P < .01). False-positive results (n = 9) occurred only on corticomedullary-phase scans because of lack of enhancement of the renal medulla. CONCLUSION: Nephrographic-phase scans enabled greater lesion detection and better characterization of small renal masses than corticomedullary-phase scans. Nephrographic-phase scans should be obtained when only monophasic scanning is used to detect small renal masses.

Extracranial aneurysm and arteriovenous fistula: embolization with the Guglielmi detachable coil.

PURPOSE: To evaluate the feasibility and safety of Guglielmi detachable coils for endovascular treatment of extracranial aneurysm and arteriovenous fistula. MATERIALS AND METHODS: Embolization with Guglielmi detachable coils delivered through Tracker-18 microcatheters was performed in 16 patients. This patient group had eight renal artery aneurysms and 11 arteriovenous fistulas (three cases of patent ductus arteriosus, one associated with aneurysm; one fistula between the maxillary artery and jugular vein; two fistulas between the subclavian and pulmonary arteries; four fistulas between the pulmonary artery and vein; and one fistula between the anterior tibial artery and vein). Efficacy of the procedure was assessed by means of short-term follow-up (clinical examination, angiography, and/or Doppler sonography) 3 and 6 months later. RESULTS: No complications were encountered. Embolization was technically and clinically successfully in all eight aneurysms (100%) and in nine arteriovenous fistulas (82%). In two cases (fistula between the subclavian and pulmonary arteries and fistula between the anterior tibial artery and vein) endovascular placement of Guglielmi detachable coils failed to occlude the vessel. Results of short-term follow-up examinations confirmed the initial results in all cases. CONCLUSION: Guglielmi detachable coils are feasible, safe, and effective for endovascular treatment of extracranial aneurysm and arteriovenous fistula.